add sd-ext support

Change-Id: Ie3be4cb4fbdf87aad04d21f0ed1a9940314e418f
Build f2fs tools

Change-Id: Iddda06c0781a1a91c80255467f7b802523a359d2
build twrp by default

Change-Id: If6c3eea0995dfaa6c445f0d58a30353c91f412d8
Revert "build twrp by default"

This reverts commit c02106c0e5ca72dcca0f0a011f2e2fad6a0ce79f.